1. Detection of rovibrationally excited molecular hydrogen in the electronic ground state via synchrotron radiation
- Author
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Béchu, S., Aleiferis, S., Bentounes, J., Gavilan, L., Shakhatov, V.A., Bès, A., Svarnas, P., Mazouffre, S., De Oliviera, N., Engeln, R., Lemaire, J.L., Béchu, S., Aleiferis, S., Bentounes, J., Gavilan, L., Shakhatov, V.A., Bès, A., Svarnas, P., Mazouffre, S., De Oliviera, N., Engeln, R., and Lemaire, J.L.
- Abstract
We describe an original setup named SCHEME (Source of exCited HydrogEn MolEcules) designed to study the recombinative desorption mechanisms of H atoms on a surface by means of high-brilliance monochromatic synchrotron radiation (SR). H atoms are produced on electrically heated filaments under vacuum (in the absence of any discharge) and subsequently recombine on a surface to produce excited hydrogen molecules, namely, H2(v″, J″). Once these levels are produced, they are probed in the vacuum chamber with 5-40 eV (248-31 nm) SR-photons. A preliminary test with Krypton has demonstrated the feasibility of SCHEME to obtain simultaneously VUV-synchrotron radiation induced fluorescence and VUV-absorption signals with room-temperature gas. In order to evaluate the hydrogen molecule dissociation induced by the heated filaments, the absolute density of H atoms has been measured by VUV-absorption. At 1800 K and 100 mTorr, we estimated a dissociation degree of 10-4, which corresponds to an absolute density of 1.8×1017 m-3. VUV-absorption spectroscopy is shown to be a valuable tool to detect H2(v″, J″) molecules up to v″ = 3. Possible improvements of the experimental setup, to detect higher v″ levels, are suggested in the end of this paper.
- Published
- 2017